Seventy-two, 4 week-old pigs were randomly assigned by sex (gilts, barrows, boars) to two dietary treatments and four age periods to determine the effect of age, sex and calcium and phosphorus levels on the mechanical properties of various bones in swine. Pigs were individually fed diets containing either .4,.4 % Ca,P (T1) or .8,.8 % Ca,P (T2). Slaughter times (age period) were approximately 1 (A1), 3 (A3), 5 (A5) or 7 (A7) months after the initiation of the trial. The femur (Fern), humerus (Hum), third and fourth metacarpal (3MC;​ 4MC), third and fourth metatarsal (3MT;​ 4MT), third rib (Rib) and thoracic vertebrae (Ver) were collected at each age period for mechanical tests and determination of percentage of ash. Bending moment, ultimate stress, yield stress and modulus of elasticity were determined by a flexure test in which the bone was treated as a simply-supported, centrally-loaded beam (three point loading).

Bones from boars withstood a force (bending moment) similar to bones from gilts or barrows. When expressed as force per unit area the ultimate stress of bones from boars was less than that of gilts or barrows. Percentage of ash was not significantly different due to sex, but tended to be lower in boars than in gilts or barrows.

Bones from pigs fed T2 had a higher bending moment than bones from pigs fed T1 regardless of age. At A1 the Fem, Hum and Rib were able to withstand a greater stress when pigs were fed T2 compared to the same bone of pigs fed T1. At A3 and A5 the ultimate stress of all bones increased as pigs were fed higher levels of Ca,P. At A7 the Fem, 4MT and Rib failed to show a response to increased levels of Ca,P.